Hot melt coating composition for film transfer and casting process

Abstract

A coating composition that can be used in a process for coating a substrate where in a first step a radiation curable coating composition is applied to the substrate and/or a radiation permeable film. Next, the substrate and the film are pressed together in such a way that the coating composition is sandwiched between them. Thereafter, the coating composition is cured by irradiation through the film to obtain a coated substrate. In a subsequent step, the film is removed from the coated substrate. The coating composition applied to the film and/or the substrate is a hot melt composition comprising 20 to 100 wt. % of a radiation curable resin or mixture of radiation curable resins having a viscosity in the range of from 15 to 10,000 mPa.s in the temperature range of from 40 to 150° C.

1. A process for coating a substrate comprising a first step of applying a radiation curable coating composition to the substrate and/or to a radiation permeable film, the coating composition being a hot melt composition comprising 20 to 100 wt. % of a radiation curable resin or mixture of radiation curable resins having a viscosity in the range of from 15 to 10,000 mPa.s in the temperature range of from 40 to 150° C.; next pressing the substrate and the film together to sandwich the coating composition between them; thereafter curing the coating composition by irradiation through the film to obtain a coated substrate; and in a subsequent step removing the film from the coated substrate. 
     
     
       2. The process according to  claim 1 , further comprising:
 a) 0 to 50 wt. % of non-radiation curable polymers,  
 b) 0 to 10 wt. % of a photoinitiator,  
 c) 0 to 50 wt. % of fillers and/or additives,  
 d) 0 to 40 wt. % of volatile organic compounds,  
 e) 0 to 50 wt. % of reactive diluents, and  
 f) 0 to 50 wt. % of pigment,  
 
       wherein the total amount of components a) to f) and the 20 to 100 wt. % of a radiation curable resin or mixture of radiation curable resins amounts to 100 wt. %. 
     
     
       3. The process according to  claim 1 , wherein the coating composition is a hot melt composition comprising a radiation curable resin or mixture of radiation curable resins having a viscosity in the range of from 15 to 4,000 mPa.s in the temperature range of from 40 to 150° C. 
     
     
       4. The process according to  claim 1 , wherein the coating composition comprises a polyester acrylate resin. 
     
     
       5. The process according to  claim 4 , wherein the coating composition comprises at least 40 wt. % of the polyester acrylate resin. 
     
     
       6. The process according to  claim 1 , wherein the substrate is a heat-sensitive substrate. 
     
     
       7. The process according to  claim 6 , wherein the substrate contains cellulose and/or plastic. 
     
     
       8. The process according to  claim 1 , further comprising allowing the uncured coating composition on the film, or on the substrate, or sandwiched between the substrate and the film, to re-flow by heating the substrate and/or the film such that the coating softens. 
     
     
       9. The process according to  claim 8 , wherein re-flow is achieved by heating and applying pressure. 
     
     
       10. The process according to  claim 1 , wherein the curing by irradiation is performed using a low energy UV source or a medium-pressure mercury lamp. 
     
     
       11. The process according to  claim 1 , wherein the step of pressing the substrate and the film together to sandwich the coating composition between them occurs without drying the coating composition. 
     
     
       12. The process according to  claim 1 , wherein the coating is applied in an amount of 3-50 g/m 2 .